yankphan said:7000 k rpm is getting me about 80-82 mph according to the speedo .... I'm sure it's about 10% fast so actually doing low 70's
when I was buying my second one, I noticed there was a difference in the engage speed of the clutch on the 2010 not much, but it got me thinking and I went back to the 2008 when I purchasedlloyd123 said:I haven't seen this mentioned before.
I was looking through the AN400/A service manual which has all the specs from 2007 through 2013 plus lists all the changes that were made.
The final drive ratio from 2007 thru 2009 is 5.904 but in 2010 Suzuki changed it to 6.484 so that would be an increase in rpm of about 10% if my math is correct(?). I would think this would give better acceleration but higher rpm for any given speed plus a reduction in gas milage. Maybe this was done to lock up the clutch faster to avoid glazing.
Great observation about the piston speed - gives me some peace of mind about running it on the interstate.Quantum Mechanic said:I too noticed the different final drive ratio. I also noticed this was accompanied by an increase in the engines maximum revs show on the tachometer (where the redline starts). It went up from 8,500rpm to 8,950rpm on all the 2010 onwards bikes.
This DOHC 400 engine is a real gem. It's tough and loves to rev even though it has plenty of low down power for normal riding. Anyone wanting to cruise fast need not worry about the engine revs too much. Remember it's a short stroke engine...so it has a relatively low piston speed at any given revs. It's not a stressed unit at any speed and is capable of sustaining high revs for long periods without harm. 7k revs is very easy going indeed and you can hold that or even more revs all day.
Reducing the RPM's will yield better fuel economy, this is the reason I wanted the RPM's decreased on my 400.osbornk said:I don't understand why so many people want to decrease the rpms on our 400s. Back in my crazy and far younger days, we spent a lot of money to put 4:11 gears in our hot rods so we could outrun others in on our mountain roads. It lowered out top end (but we didn't have enough straight roads to go that fast). Since I ride crooked mountain roads, I like the higher rpms. I took a jaunt down the interstate today and ran mine at 7,400 rpms for a good while.
I also noticed in the AN400 service manual that Suziuki changed the design of the top compression piston ring. From 2007 to 2009 it was similar - same thickness throughout - to the second compression ring but in 2010 it was redesigned to have a dual thickness - "a" and "b". I'm not an engineer but perhaps this design allowed the redline to be increased as well.Quantum Mechanic said:I suspect the tacho redline has been moved to compensate for the slightly lower gearing.